Question

trigonometry

Answer 1

http://gyazo.com/73716d6df060baff67f98b62e4e6f7ef

Answer 2

@Mertsj

Answer 3

\[5(\cos y+\sin y)(2\cos y-\sin y)=7\]

Answer 4

\[5(2\cos ^2y-\sin y \cos y+2\sin y \cos y-\sin ^2y)-7=0\]

Answer 5

when I expand it, this is what I get,
\[10\cos ^{2}y+5sinycosy-5\sin ^{2}y-7=0\]

Answer 6

Yep. Me too. But that doesn't seem very helpful/.

Answer 7

i found it! thank you for your help....

Answer 8

What did you do?

Answer 9

divide through by cos^2 y and what do you get??

Answer 10

Oh. of course. Good going!!

Answer 11

this is what I got,
\[10+5tany-5\tan ^{2}y-7\sec ^{2}y=0\]
\[10+5tany-5\tan ^{2}y-7(\tan^{2}y+1)=0\]
from there, I arrived at the answer..

Answer 12

exactly. Very good.